Warriors and Kiwis playmaker Shaun Johnson's knee injury isn't as serious as first feared, enabling him to play in this year's Rugby League World Cup.

Shaun Johnson's Rugby League World Cup dream is still alive - but his 2017 Warriors campaign is all but over.

The star Warriors and Kiwis playmaker was diagnosed with a rupture to the posterior cruciate ligament in his left knee on Monday afternoon, after buckling over in his side's 34-22 loss to Penrith on Friday.

Club doctors initially feared the worst for Johnson, who had already missed a large chunk of football in 2015 with a broken ankle.

But, in news that will provide much relief for David Kidwell and little for Stephen Kearney, Johnson will only miss six to eight weeks of action.

That's enough to miss almost all of the 11th-placed Warriors' seven remaining games, five of which they need to win to sneak into the top eight.

But he's all but certain to pull on the black-and-white jumper for the Kiwis in November's World Cup, as they attempt to wrestle back the trophy from Australia.

The 26-year-old won't need an operation.

"This is a much better outcome than we had expected," Warriors team doctor John Mayhew said in a statement.

"We had believed the injury was likely to be an ACL (anterior cruciate ligament), but scans have indicated this isn't so, and Shaun won't need surgical intervention to repair the injury."

After his side's late defeat to Penrith, Kearney admitted Johnson's 62nd-minute injury - with the Warriors up 22-18 - may have sapped his side.

They conceded three late tries at home to lose the match.

"That possibly played a bit of a part," Kearney told reporters.

Young gun Ata Hingano, who has made seven NRL appearances in 2017, is likely to partner Kieran Foran in the Warriors' halves in Johnson's absence.